Noninvasive Blood Pressure
An oscillometric cuff records small pressure oscillations caused by each heartbeat while the cuff deflates. The cuff pressure at the largest oscillation is linked, in a simplified approach, to mean arterial pressure.
Synthetic measurement
Controls
Why these controls?
These sliders set a complete measurement cycle: starting cuff pressure and deflation speed, the true arterial pressure behind the synthetic envelope, pulse rate, noise, and the two teaching ratios. Change them to see the envelope peak at MAP and how fast deflation or noise disturbs the estimates.
Envelope: dashed = set synthetic envelope, dots = per-beat measured amplitude. Pressure axis runs high → low, in deflation order.
Simplified MAP estimate
94 mmHg
Set MAP: 93 mmHg
Teaching systolic point
113 mmHg
Amplitude = 0.55 × Amax (above MAP)
Teaching diastolic point
79 mmHg
Amplitude = 0.75 × Amax (below MAP)
Beats recorded
60
Deflation lasts 50.0 s
No reliability warnings in this synthetic run
Model
Formulas & units
Pcuff(t) = P0 − r·t (mmHg, mmHg/s, s)
A(P) = Amax·exp(−(P − MAP)² / 2σ²)
MAPest = Pcuff at max A
SYS/DIA = Pcuff where A = k·Amax
Important
The systolic and diastolic ratios here are teaching values, not a manufacturer algorithm. Real devices estimate systolic and diastolic pressure with device-specific and usually proprietary (closed) algorithms; a fixed-ratio approach is not a universal clinical algorithm. Changing the ratio moves the points along the same envelope, which is exactly why results depend on the chosen algorithm.
Student checks
- With zero noise and slow deflation, verify that the envelope maximum occurs at the set MAP.
- Increase deflation rate or noise and analyse how the estimated MAP and envelope shape change.
- Change the systolic/diastolic ratios, explain why the results change, and why clinical algorithms are device-specific.
- In the irregular-pulse scenario, discuss which model assumption (regular beats, beat-to-beat constant amplitude) breaks down.